Photographic emulsion layers



Patented Sept. 4, 1945 PHOTOGRAPHIC EMULSION LAYERS Merlin MartinBrubaker, Boothwyn, Pa., assignor to E. I. du Pont de Nemours & Company,Wilmington, Del., a corporation of Delaware No Drawing. Application May4, 1944, Serial No. 534,157

4 Claims.

to aqueous solutions with consequent slow processing. In addition,special methods of dispersion must be used, and only emulsions of lowspeed can be obtained. Gelatin, which is-much more water-sensitive thancollodion, was later used as the binder for the light-sensitive silverhalide and, although it is much more satisfactory than collodion, andenjoys widespread commercial use, it possesses a number ofdisadvantages. Among these may be cited its sensitivity to bacterialdecomposition, low stability to heat, brittleness at normal temperatureand humidity, nonuniformity of various lots, and limited range ofprocessing temperatures. Other materials which have been used asemulsion binders include albumin, agar-agar, casein, polyvinyl alcoholderivatives in conjunction with special dispersing and gelling agentsand cellulosic derivatives.

An object of this invention is to provide new and useful photographicelements which are free from the disadvantage of gelatin. Another objectis to provide water-permeable colloid layers which are tough,strong'and'flexible. Another object is to provide such layers which donot dissolve or become weak in water at ordinary temperatures. Yetanother object is to provide silver halide emulsion layers of uniformquality and sensitivity. Still other objects will be apparent from thefollowing description of the invention.

The above objects are accomplished by the preparation of photographicelements bearing at least one layer composed essentially of ahydrophilic'synthetic linear polycarbonamide contain-- ing intralinearoxygen atoms which polycarbonamide is insoluble in water'at 2010. butsoluble to the extent of at least five percent in water containing 40per cent ethanol at 70 C.

The use of synthetic polyamide-layers in photographic elements has beenproposed. However,

these materials vary quite-widely in physical 55 properties as well asin structure and chemical properties. The simple polyamides from adibasic carboxylic acid and a diamine contaimng only carbon and nitrogenatoms in the polymer chain, for example, yield films which arecompletely insoluble in water and the usual organic solvents, includingethanol and ethanol-water mixtures, and are capable of absorbingonlyfrom eight to nine per cent of water. Interpolymers of suchpolyamides with a third polyamide-formlng component such as anaminocarboxylic acid or a lactam, e. g., aminocaproic acid orcaprolactam,

result in products which are soluble in ethanol containing 10 to 30 percent of water. These polymers also have. a low water absorption (e. g.,10 to 15 per cent) and dry films are relatively impermeable sto water.Interpolymers which contain a large number of ether groups per molecule,on the other hand, are water-soluble and therefore not satisfactory. aspermanent layers for photographic elements. They wash offfrom a Supportduring photographic processing unlessa material amount of'a colloid suchas gelatin is present.

It has been found, however, that the above objects may be attained andthe above disadvantages overcome by using a special class ofinterpolyamides possessing recurring intralinear oxygen atoms in therati of one oxygen atom to each '7 to 16 carbon atoms and which possessthe above solubility characteristics. The intralinear oxygen atoms orether groups may be present in either the diamine or dibasic acidconstituent or both. The proportion of oxygen and carbon atoms can beadjusted by choosing the proper. amideiorming components. When one ortwo componentswill not produce a synthetic linear .polyamide with theaforesaid ratio of oxygen carbon and nitrogen atoms, additionalpolyamide forming components can be added or two polyamides of'lowmolecular weight or having a low degree of polymerization can beinterpolymerized until the desired molecular weight is attained.Interpolyamides, j for example, which contain one intralinear oxygenatom for each six carbon atoms are not satisfactory as binding agentsfor light-sensitive silver salts in thin photog-raphic layers. Forexample, polytriglycoladipamide containing one oxygen atom for every sixcarbon atoms is too water-sensitive to be used alone as a gelatinsubstitute in photographic emulsions. However, by interpolymerizingtriglycoladipamide with a'dibasic acid and diamine combination, leadingt a lower ratio of oxy en atoms in the chain, desirable products can beobtained. Thus, a hexamethyleneadipamide/triglycoladipamide interpolymercomposed of equal mole ratios of the two components yields apolycontaining on oxygen atom for every 12' carbon atoms in the polymerchain. This material is found to have the desired solubility andpermeability requirements for use .in photographic emulsions.

The invention admits of the use of a fairly wide variety of polyamidescontaining recurring intralinear oxygen atoms. As exemplary polymers,mention is made of the following: 1) polymerizates of3,3'-diaminodipropyl ether with sebacic acid, (2) polymerizates ofbis-aminopropoxyethane with sebacic acid, (3) polymerizates o1"diglycolic acid and decamethylenediamine, (4) interpolymerizates oftriglycoldiammonium adipate containing to 60 moi per centhexamethylenediammonium adipate, (5) interpolymerizates of thebis-aminopropoxyethanedi- V glycolic acid salt with 43 to 73 mol percent of hexamethylenediammonium adipate, (6) polymerizates of3,3'-diaminodipropyl ether and suberic acid. I

In addition to the water-sensitive polyamides I described above whichare formed wholly from amide-forming reactants, mixed condensation,

polymers can be used, e. g., polyesteramides from glycols, dibasic acidsand diamines, which contain intralinear oxygen atoms in the ratioof onefor every seven to sixteen carbon atoms. The

polymers in which the intralinear oxygen atom is present in the ratio ofone to every eight to fourteen carbon atoms have been found particularlydesirable and form the preferred embodiment of this invention.

The preparation of the above and other suitable polyamides is describedin United States Patents 2,158,064 and 2,191,558. Polyamides of theabove type are dissolved in water containing from 5 to 40 per cent ofethanol, an insoluble photographic emulsion constituent is incorporatedtherewith and the resulting solution or dispersion is coated onto asupport such as paper,

metal, glass or a transparent film base. The resulting element is thendried. In the preferred aspect of the invention polyamides having theabove characteristics are dissolved in water containing from 5 to percent of ethanol and light-sensitive silver salts are dispersedtherethrough. This may advantageously be accomplished by dissolving asoluble ionizable halide in the solution of the polymer and adding asolution of a soluble ionizable silver salt with stirring. The resultingemulsion can then be ripened, chilled or precipitated, freed from excesssoluble salts, digested, and modified by addition of more of the samepolyamides, general emulsion sensitizers, antifogging agents, spectralsensitizing dyes; preservatives, and hardeners, etc.

Soluble salts may be removed from the polyamide emulsion, aifter theripening operat on. by coagulating the emulsion with a large volume ofand washing the coagulated mass with water. The washed light-sensitivepolyamide dispersion is thendissolvedby heating with water containingalcohol and, if desired, an additional amount .of the polyamide.solution. After digestion theemulsion is coated upon a suitable support.e. 3., metal, paper, glass, or a transparent film. such as cellulosenitrate, cellulose acetate, or a synyl/formal, polyh'examethyleneadipamide, etc.

' contrast.

acetone or a soluble salt such as sodium sulfate thetic igin'orsuper-polymer such as polyvin- After drying, Dreferablyat elevatedtemperatures,

the resulting light-sensitive film element canbe used in the same manneras ordinary gelatin/silver halide light-sensitive elements with similarresults. For instance, it may be exposed and the latent image developedin a standard p-methylaminophenolsulfate/hydroquinone type developer ata temperature of 18 to 35 C. and flxed in an acid hypo bath. Theresulting negative can then be printed by standard photographic methodson any light-sensitive material of suitable speed, such asgelatin/silver halide element or onto a similar element prepared withthe polyamides hereof. p

The invention will be further illustrated but is not intended to belimited by the following examples wherein the parts stated are parts byweight and all operations are conducted under conditions which will notfog or expose the silver salts. I

Example I To a mixture containing. three parts of hexa-. methyleneadipamide/triglycoladipamide interpolymer containing the components inthe ratio of parts of the former to 75 parts of the latter, 50 parts ofwater and ten .parts of ethanol is added with stirring at 40-60 C. thefollowing two solutions: .(1) ten parts of-ammonium bromide in parts ofwater and eight parts of alcohol, (2) 11 parts of silver nitrate, 25parts of water, eight parts of alcohol, and sufilcient ammoniumhydroxide to form a clear solution. The fluid emulsion is ripenedby"stirring at 40- 60 C. for 15 minutes or more, followed by the additionof 50 parts 'of a solution containing five parts of interpolymer, tenparts of alcohol, and parts of water. The interpolymer-silver halidedispersion is then coagulated by the addition of an excess of anonsolvent such as acetone and separated by decantation or filtration.After washing free of soluble salts, the coagulate is redispersed in aten' per centsolution of the interpolymer in aqueous alcohol anddigested a suitable length of time at 4060 C. The light-sensi-' tivephotographic emulsion thusobtained is coated on paper-or a celluloseacetate film base and exposed to an image and developed at 18-20 C.

in a solution of the following composition for one to three minutes.

- The element bearing the developed image is'fixed in-a 25 per' centsolution of sodium thiosulfate,

washed and dried. The resulting film contains a black silver image ofgood density, definition and v v i J i The aforesaid interpolyamide isprepared from the salt derived from hexamethylenediamine and adipic acid(25 parts).- and salt derived from triglycoldiamine and-adipic acid'(75.part s) by heat-- ing in a sealed tube at-200 to. 210 C. for twohours, thenone hour at 256? -C. blanketed with nitrogen atatmosphericpressure. and finally'for one hour at 256 C. under a vacuumof 1 5mm.

, E's-ample II A polyamide was prepared by heating thejsaltofbis(aminopropoxy) ethane with adipic acid in a sealed tube at 200+220 C.for two and one half hours and then at 250 C. for one houratat-' sults.

. ment. Thus they may mospheric pressure in an atmosphere of nitrogenand finally at about 250 C. under a vacuum of 1 mm. The resultingpolymer was substituted for the interpolymer of Example I and a silverhalide dispersion made and coated in the same manner as described inExample I. The resulting photographic elements were then processed afterthe manner set forth in Example I with similar re- In place of theparticular hydrophilc superpolyamides may be substituted other suchpolymers which have the above characteristics. Thus the polymers ofitems (1) to (6) inclusive described above can be used in like manner.Mixtures of any of such polymers can be used if desired.

In place of-the ammonium bromide of the examples there may besubstituted other ionizable water soluble halides, e. g.,ammoniumchloride, potassium bromide, sodium bromide, sodium iodide,ammonium iodide, lithium bromide, lithium chloride. used to make mixedsilver halide dispersions if desired. Various other radiation sensitivematerials may be used in the layers such as lightsensitive diazoniumsalts, e. g., diazotized p-aminodiethylaniline or p-aminodiphenylamine;dichromates, e. g., ammonium dichromate; fulgides; heat sensitive layersof silver or mercurous oxide,

etc.

Color yielding photographic elements can be made by introducing colorformers into'the poly amide silver halide dispersions if desired. Usefulcompounds include phenols, naphthols, aromatic primary and secondaryamines, Pyrazolones, coumaranones, nitrobenzylcyanides, acylacetamides,acylacetic acid esters, homophthalylamines, cyanoacetamides, etc., whichare immobile in colloid layers. Suitable color formers are disclosed inUnited 2,140,540; 2,166,181; 2,182,815; 2,184,303; 2,200,- 924;2,283,276; 2,294,909; 2,299,641; 2,310,943, etc.

States Patents 2,133,937;.

given in the aboveexamples there Mixtures of these compounds can beImmobile types can be used in layers of elements which are given adevelopment in a solution containing a primary aromatic amino colordeveloping agent. They may be added from a dilute alkaline solution suchas a 10 per cent aqueous solution of sodium carbonate or sodiumhydroxide or an aqueous ethanol solution.

In additionvarious other emulsion constituents may be added such asgeneral emulsion sensitizers, e. g., sodium suliite, sodium thiosulfate,allylthiourea, thiourea, allyl isothiocyanate.

The novel polyamides are not limited in their use to light-sensitivelayers of photographic elements, but may be used as a binding agent ormedium for any water permeable, layer of such elements. Thus, they maybe used for antihalation or filter layers which contain colloidal silveror actinic light-absorbing dyes.

They may also be used as color yielding layers and contain a dyeintermediate or color former which is coated onto a light-sensitivecolloid silver halide layer. Or they may be used in elements free fromlight-sensitive layers or in inoperative association with such layers,and used in processes of forming dye images by color couplingdevelopment, by imbibition or contact developbe used in elements orprocedures of the type described in United States Patent 2,328,034.

Separator or antiabrasion or protective layers can also be made of thenovel polyamides hereof. In the case of separator layers they maycontain a filter dye, e. g., 'tartrazine Colour Index No. 640.

the dyes of United States Patent 2,258,609, for example Safranine GColour Index No. 841, Helianthine Colour Index Nos. 142 and 146,Brilliant Yellow S Colour Index No. 144, Sairanine 0 Colour Index No.841 and Metanil Yellow Colour Index No. 138, as a yellow filter layerfor a multilayer elemnt. The layer can be placed between a bluesensitive polyamide silver halide layer and a green-sensitive polyamidesilver halide layer which is disposed on a red-sensitive polyamidesilver halide layer.

The elements may be used as a negative or positive stock, forlithographic purposes, X-ray film, motion picture film, color film andin fact for any purpose for which elements containing gelatin layers canbe used.

An advantage of the invention resides in the fact that photographicelements with water-per:- meable layers which are uniform in propertiescan be readily prepared. Other advantages are:

(1) film elements are relatively unaffected by conditions of highhumidity, (2) film elements do not crack under conditions of lowrelative humidity, (3) the emulsion is not attacked by bacteria, and (4)the new emulsions are particularl suitable for use on a superpolyamidesupport because of good adhesion therefor.

Since it is obvious that many changes and modifications can be made inthe above-described details without departing from the nature and,

spirit of the invention, it is to be understood that the invention isnot to be limited to the details described herein except as set forth inthe appended claims.

What is claimed is:

1. A photographic element comprising a support bearing at least onewater-permeable layer consisting of a hydrophilic synthetic linearpolycarbonamide. containing recurring intralinear oxygen atoms andrecurring intralinear amide groups, said oxygen atoms being present inthe ratio of one atom to each 7 to 16 carbon atoms, which is insolublein water at 20 C., but soluble to the extent of at least five per centin water containing 40 per cent ethanol at 70 C., said layer havinglight-sensitive silver halides dispersed therethrough.

A photographic element comprising a support bearing at least onewater-permeable layer 'poxy) ethane in water at 20 0., but soluble tothe extent of at least 5 per cent by weight in water containing 40 percent ethanol at 0., said layer having lightsensitive silver halidesdispersed therethrough.

4. A photographic element comprising a support bearing at least onewater-permeable layer consisting of a polymerizate of3,3-diaminodipropyl ether with sebacic acid which is insoluble in waterat 20 least 5% in water containing 40% ethanol at 70 7 C., said layerhaving light-sensitive silver halides dispersed therethrough.

MERLIN MARTIN BRUBAKER.

C., but soluble to the extent of at 1

